Flowable materials are commonly dispensed from pressurized containers. In many such containers, a gaseous propellent is mixed with the flowable material product, thus providing the motive force to expel the product from the container. One example of such a container is an aerosol can in which a propellant gas is provided to drive a liquid or an atomized gas-liquid mixture product from the container. In such containers, the initial pressure within the container often declines as the product is dispensed.
Although this type of pressurization system works adequately with some products, in many applications it is undesirable to mix the propellant gas with the product being dispensed. Such mixing may result in undesirable reactions between the product and the propellant, thus leading to a degradation of the product.
It is also undesirable to dispense many products with a declining pressure dispensing system. This is particularly true with carbonated liquid products, such as beer. It has been found that successfully dispensing carbonated liquids depends, in part, upon maintaining a predetermined relatively constant pressure differential between the inside of the container and the ambient environment. In a declining pressure dispensing system, this is generally not possible.
To overcome the problems discussed above, a pressurization system has been developed in which an expansible pressure pouch is placed within the product container. The pressure pouch includes a plurality of chemicals contained in a series of compartments within the pouch. When mixed together, the chemicals in the pouch generate gas and pressure, thus expanding the pouch and providing pressure to drive the product from the container. As product is dispensed from the container, the pouch expands, causing more compartments to open. This, in turn, causes the introduction and mixing of more gas-generating chemicals and, thus, the development of more pressure within the container. The expansible pouch, thus, provides the dual functions of separating the propellant gas from the product and of maintaining a relatively constant pressure profile within the container.
Examples of dispensing systems and components thereof useable in conjunction with expansible pressure pouches are described in U.S. Pat. No. 5,050,806 to Anderson et al.; U.S. Pat. No. 4,739,901 to Dorfman et al.; U.S. Pat. No. 4,867,348 to Dorfman; U.S. patent application Ser. No. 09/362,483 filed Jul. 28, 1999, of Lowell T. Whitney et al. for METHOD AND APPARATUS FOR DISPENSING A LIQUID CONTAINING GAS IN SOLUTION; U.S. Pat. No. 6,164,492 to Michael L. Lane et al. for READILY DEFORMABLE PRESSURE SYSTEM FOR DISPENSING FLUID FROM A CONTAINER and U.S. patent application Ser. No. 09/535,338 filed Mar. 24, 2000 of Michael L. Lane et al. for APPARATUS AND METHOD FOR VARIABLY RESTRICTING FLOW IN A PRESSURIZED DISPENSING SYSTEM, which are all hereby specifically incorporated by reference for all that is disclosed therein.
Expansible pressure pouches may be formed by juxtaposing two sheets of flexible plastic material. The pouch compartments discussed above may be formed by releasably attaching one sheet to the other at selected seam locations, e.g., via a heat sealing technique. As the pouch expands, each releasable seam may be opened or peeled in a sequential manner to release more gas-generating chemical in a manner as described above. Examples of such expansible pressure pouches using peelable seam technology are disclosed in U.S. Pat. No. 4,785,972 to LeFevre; U.S. Pat. No. 4,919,310 to Young et al.; U.S. Pat. No. 4,923,095 to Dorfman et al. and U.S. Pat. No. 5,333,763 to Lane et al., which are all hereby specifically incorporated by reference for all that is disclosed therein.
As an alternative to peelable seams, the compartments of some pressure pouches are separated by frangible wall portions which fail or tear in response to increasing volume of an adjacent compartment. An example of a pressure pouch using such frangible divider wall portions is disclosed in U.S. Pat. No. 5,769,282 to Lane et al. which is hereby specifically incorporated by reference for all that is disclosed therein.
In either type of pressure pouch described above, the plastic film used to form the pressure pouch must be capable of performing several functions. First, the outer surfaces of the film (i.e., the surface of the film that will form the outer surface of the pressure pouch) must be compatible with the product to be dispensed from the container. This means that the outer surfaces must be generally non-reactive with the product and, in the case of food products, that they not impart any appreciable flavor to the product.
In most cases, the film must also be relatively gas-impermeable in order to prevent the pressurizing gases generated within the pressure pouch from migrating into and mixing with the product in the container. The film also must be capable of forming reliable permanent seams in order to seal the outer periphery of the pressure pouch.
In the case of a peelable seam type pressure pouch, the film used to form the pouch must additionally be capable of forming reliable peelable seams. For successful operation of a peelable seam type pressure pouch, the peelable seams must be formed such that a specific and narrow range of force will cause opening of the peelable seams. If the peelable seams are formed with too much strength, they may, in essence, become permanent seams. If this occurs, the peelable seams may fail to separate or may tear the plastic layers when the pressure pouch is activated, in either case resulting in a defective pressure pouch. If the peelable seams are formed with too little strength, they may open prematurely, possibly leading to premature activation of the pouch or in defective operation thereof.
In a typical pressure pouch dispensing system, the dispensing container is generally first filled with a flowable product to be dispensed from the container. The pressure pouch is then inserted into the dispensing container and submerged within the flowable product contained therein. The container is then sealed, e.g., by attaching a valve assembly to the container opening.
The above operations generally take place with the container in a vertical orientation, i.e., with the container opening facing upwardly. Typically, filled dispensing containers are also shipped in a vertical orientation.
After the container is sealed, the pressure pouch is activated, thus applying pressure to the product in the container. This pressure is used to force product from the container when it is desired to dispense product from the container. In the case where the container is used for a gas-containing flowable product, this pressure also serves to maintain the gas in solution. After the pressure pouch is activated, any gas headspace trapped within the container may be bled off, for example, by opening the valve assembly. Alternatively, the gas headspace may be left in the container. If left in the container, the gas headspace may eventually be forced into solution within the flowable product by the pressure supplied by the pressure pouch.
As mentioned above, filling and shipping operations generally occur with the dispensing container in a vertical orientation. The container is generally, however, placed in a horizontal orientation, i.e., with the container opening and valve assembly facing horizontally, when it is desired to dispense product from the container.
Before a pressure pouch dispensing system is used for the first time (i.e., before any fluid is dispensed from the container), the pressure pouch, although activated, is in a relatively unexpanded condition. In other words, the fluid in the container occupies a relatively large volume while the pressure pouch occupies a relatively small volume. As product is dispensed from the container, this situation tends to reverse; as fluid is dispensed from the container, the volume of fluid in the container decreases, and the volume of the pressure pouch expands.
In order for all of the fluid to be expended from the container, it is necessary that the pressure pouch be capable of substantially conforming to the shape of the container when the pressure pouch is fully expanded. As can be appreciated, in order to achieve this, it is necessary for the pressure pouch, in its initial unexpanded condition, to have a length that is longer than the available length within the container.
Thus, when the pressure pouch is first inserted into the container (i.e., before the pressure pouch is activated and the container sealed), the length of the pressure pouch is longer than the available length of the container. In order to fit the relatively longer pressure pouch into the relatively shorter container, it is conventional to fold the pressure pouch about a fold line prior to installing the pressure pouch into the container.
The pressure pouch, in its initial configuration, also typically has a greater width than the width of the container opening. Accordingly, in order to fit the pouch through the container opening, it is conventional to also fan-fold the pouch prior to installing the pressure pouch into the container.
With the pressure pouch folded in this manner, it will fit completely within the available space inside the container. Folding of the pouch is also important to assure that the pressure pouch deploys properly during product dispensing.
Pressure pouches are commonly manufactured at a location which is remote from the location at which dispensing containers are filled. Furthermore, pressure pouches are typically manufactured in bulk and stored for future use. In order to ensure that pressure pouches are properly folded, as described above, and that the folding is maintained until it is time for the pouch to be inserted into a container, it is conventional to place each pressure pouch within an outer shipping pouch immediately after the pressure pouch is folded.
When it is time to insert the pressure pouch into a dispensing container, the shipping pouch may be cut open and positioned above the open end of the filled container. Thereafter, the pressure pouch may be allowed to slide out of the shipping pouch and drop into the container. The shipping pouch, which does not enter the container, may then be discarded.
The shipping pouch, thus, serves to maintain the proper folded configuration of the pressure pouch until it is inserted into the container. The shipping pouch may also function to preserve the sterility of the pressure pouch. Specifically, the pressure pouch may be sterilized after being manufactured. It may then be folded in a sterile environment and then sealed within the shipping pouch. The sterility of the pressure pouch, thus, is preserved by the shipping pouch.
Although the above described pressure pouch and shipping pouch generally work well, it has been found that, under some circumstances, some of the reactive components within the pressure pouch can become trapped by the pouch fold when the container is in its vertical filling orientation. This may result in there not being enough reactive component to completely react and, thus, in improper operation of the pressure pouch.
Accordingly, it would be generally desirable to provide an apparatus and method which overcomes these problems associated with flowable product dispensing pressure systems.